Loop heat pipe structure

ABSTRACT

A loop heat pipe structure includes an evaporation chamber body and a tube body. The evaporation chamber body has an upper case body and a lower board body. The upper case body and the lower board body together define a closed chamber in which a capillary structure is disposed. The evaporation chamber body has an outlet and an inlet in communication with the closed chamber. A working fluid is filled in the closed chamber. Two ends of the tube body are respectively connected with the outlet and the inlet. The upper case body and the lower board body of the evaporation chamber body and the tube body are made of various materials in combination with each other so as to improve the shortcoming of the conventional loop heat pipe that the strength is insufficient and reduce the total weight of the loop heat pipe.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates generally to a loop heat pipe structure,and more particularly to a loop heat pipe structure, in which titaniumor stainless steel material is used instead of the upper cover body andthe condensation tube body of the evaporation chamber body of theconventional loop heat pipe so as to enhance the structural strength ofthe entire loop heat pipe and reduce the total weight of the loop heatpipe.

2. Description of the Related Art

Along with the increase of the performance of the current electronicapparatuses, the heat generated by the electronic components for signalprocessing and operation has become higher than the conventionalelectronic components. The most often used heat dissipation componentsinclude heat pipe, heat sink, vapor chamber, etc. These heat dissipationcomponents are in direct contact with the heat generation electroniccomponents to enhance the heat dissipation performance so as to preventthe electronic components from burning out due to over-heating.

A fan with forced heat dissipation effect can be further disposed todissipate the heat of the heat dissipation component. The fan can trulyenhance the heat dissipation performance. However, it is not alwayspracticable to arrange a fan in a limited space. Therefore, the spaceproblem is also a key point needing to be taken into consideration.

In addition, some manufacturers in this field provide a loop heat pipestructure in concept of heat pipe vapor-liquid circulation. The loopheat pipe structure is composed of an evaporation chamber body and acondensation device in combination with the evaporation chamber body. Atube body is connected between the evaporation chamber body and thecondensation device to form the loop heat pipe structure as a loopmodule. The loop heat pipe structure has the advantage that the loopheat pipe structure can provide a heat dissipation device with betterevaporation-condensation circulation effect itself. A capillarystructure is disposed in the evaporation chamber body for the workingfluid to flow back and store. The capillary structure is formed withmultiple channels for the vapor to flow. At least one face of theevaporation chamber body is in contact with a heat source to conduct theheat. After the working fluid in the capillary structure of theevaporation chamber body is heated and evaporated, the vapor workingfluid flows out from the channels and spreads through the tube bodyconnected between the evaporation chamber body and the condensationdevice to the condensation device. Finally, the vapor working fluid iscondensed by the condensation device into liquid working fluid to flowback to the evaporation chamber body to continue the circulation.

A common loop heat pipe structure body is mainly made of copper oraluminum material. Copper has a property of high heat conductivity.However, copper is soft and has heavy weight. Aluminum has the advantageof light weight, but the heat conductivity of aluminum is poorer.Therefore, the current loop heat pipe structure fails to have all thefeatures of good heat dissipation effect and light weight and goodstructural strength.

It is therefore tried by the applicant to provide a loop heat pipestructure to improve the shortcomings of the conventional loop heatpipe.

SUMMARY OF THE INVENTION

It is therefore a primary object of the present invention to provide aloop heat pipe structure, which can reduce the total weight and keephaving high heat conductivity.

To achieve the above and other objects, the loop heat pipe structure ofthe present invention includes an evaporation chamber body and a tubebody.

The evaporation chamber body has an upper case body and a lower boardbody. The upper case body and the lower board body together define aclosed chamber in which a capillary structure is disposed. Theevaporation chamber body has an outlet and an inlet in communicationwith the closed chamber. A working fluid is filled in the closedchamber. The tube body has a first end, a second end and a middlesection. The first and second ends are respectively positioned at twoends of the middle section. The first and second ends are respectivelyconnected with the outlet and inlet of the evaporation chamber body. Theupper case body, the lower board body and the tube body are made ofmaterials selected from a group consisting of titanium, stainless steel,copper, ceramic, aluminum, iron and graphite. The titanium material iscommercial pure titanium or titanium alloy.

The upper case body and the lower board body of the evaporation chamberbody and the tube body are made of various materials in combination witheach other so as to improve the shortcomings of the conventional loopheat pipe that the strength is poor and the weight is heavy.

BRIEF DESCRIPTION OF THE DRAWINGS

The structure and the technical means adopted by the present inventionto achieve the above and other objects can be best understood byreferring to the following detailed description of the preferredembodiments and the accompanying drawings, wherein:

FIG. 1 is a perspective exploded view of a first embodiment of the loopheat structure of the present invention;

FIG. 2 is a sectional assembled view of the first embodiment of the loopheat structure of the present invention;

FIG. 3 is a sectional assembled view of a second embodiment of the loopheat structure of the present invention;

FIG. 4 is a sectional assembled view of a third embodiment of the loopheat structure of the present invention; and

FIG. 5 is a sectional view showing the operation of the loop heatstructure of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Please refer to FIGS. 1 and 2. FIG. 1 is a perspective exploded view ofa first embodiment of the loop heat structure of the present invention.FIG. 2 is a sectional assembled view of the first embodiment of the loopheat structure of the present invention. As shown in the drawings, theloop heat pipe structure 1 of the present invention includes anevaporation chamber body 11 and a tube body 12.

The evaporation chamber body 11 has an upper case body 111 and a lowerboard body 112. The upper case body 111 and the lower board body 112together define a closed chamber 113 in which a capillary structure 2 isdisposed. The evaporation chamber body 11 has an outlet 114 and an inlet115 in communication with the closed chamber 113. A working fluid 3 isfilled in the closed chamber 113.

The tube body 12 has a first end 121 and a second end 122 and a middlesection 123. The first and second ends 121, 122 are respectivelypositioned at two ends of the middle section 123. The first and secondends 121, 122 are respectively connected with the outlet and inlet 114,115 of the evaporation chamber body 11. A heat dissipation unit 4 isdisposed on outer side of the tube body 12. The heat dissipation unit 4serves to enhance the condensation efficiency of the tube body 12. Theheat dissipation unit 4 can be a radiating fin assembly or a heat sinkor any other form of heat dissipation unit 4 or multiple cooling tubebodies capable of increasing heat dissipation or cooling area. In thisembodiment, the heat dissipation unit 4 is, but not limited to, aradiating fin assembly for illustration purposes. The upper case body111, the lower board body 112, the tube body 12 and the capillarystructure 2 are made of a material selected from a group consisting oftitanium, stainless steel, copper, ceramic, aluminum, iron and graphite.

The closed chamber 113 further has at least one vapor passage 116 and acompensation chamber 117. The vapor passage 116 is selectively disposedon a wall face of the evaporation chamber body 11, which faces thecapillary structure 2 or disposed on one side of the capillary structure2, which faces the evaporation chamber body 11. In addition, one end ofthe vapor passage 116 is correspondingly connected with the outlet 114.The working fluid 3 is converted between vapor phase and liquid phase.The vapor-phase working fluid 31 and the liquid-phase working fluid 32are circulated within the entire interior of the loop heat pipestructure 1. The evaporation chamber body 11 is a flat-plate evaporationchamber body. The compensation chamber 117 is correspondingly disposedin parallel to the capillary structure 2.

The capillary structure 2 has multiple channels 21 in adjacency to thelower board body 112. Each channel 21 has an open side 211 and a closedside 212. The open side 211 is attached to the lower board body 212. Theopen side 211 has a width smaller than that of the closed side 212.

The capillary structure 2 is formed of sintered powder. The powder isselected from a group consisting of copper, aluminum, titanium andplastic fiber.

The titanium material is commercial pure titanium or titanium alloy. Thecommercial pure titanium and titanium alloy have nine properties of highspecific strength, excellent anticorrosion ability, low elastic modulus,good heat-resistance, excellent low-temperature property, highbiological compatibility, low heat conductivity, colorful oxide film andnon-magnetic. The commercial pure titanium and titanium alloy are widelyapplied to civil industries, petrochemical industries, aerospaceindustries, military industries, medical industries, etc. In recentyears, various countries have developed over 100 types of titaniumalloys. There are about 40˜50 types of actually commercialized titaniumalloys. According to the elements contained in the titanium alloys, thetitanium alloys can be generally classified into three major types, thatis, α-type titanium, α-β-type titanium and β-type titanium: (1) α-typetitanium can be classified into commercial pure titanium, α titanium andnear α titanium according to the sort and content of the containedelement. The commercial pure titanium only contains minor elements ofoxygen, carbon, nitrogen, hydrogen, iron, etc. without other alloyelement. In pure titanium, oxygen is gap-type element. The content ofoxygen greatly affects the strength of the pure titanium. In general,0.1 wt % oxygen will about 100˜120 MPa increase the strength of thetitanium. According to the content of oxygen, the commercial puretitanium can be classified into four ranks (Gr.1˜Gr.4). Grade 1 puretitanium has oxygen content lower than 0.18 wt % and has the advantagesof low strength, excellent ductility and good formability and is mainlyapplied to building roof and plate-type heat exchanger. Grade 2 puretitanium has tension strength ranging from 350-450 MPa and is the mostoften used one of the four types of pure titanium. Grade 2 pure titaniumis often applied to manufacturing of seam pipe, seamless pipe andchemical engineering tank. Grade 3 pure titanium has strength rangingfrom about 500-600 MPa and is mainly applied to chemical engineeringpressure tank. Grade 4 pure titanium has strength proximate to 700 MPa,which is highest among the four types of pure titanium. Grade 4 puretitanium is mainly applied to some fastening members and complicatedcomponents needing to form at about 300° C. α titanium contains αstabilizing elements (Al, O) and neutral elements (Sn, Zr). Afterannealed, the texture is single-phase a having good texture stability,heat-resistance and weldability and having strength higher thanindustrial pure titanium. In order to satisfy strength requirement,neutral element will be added into α-type titanium alloy to reinforcethe same. The most typical example is Gr.6(Ti-5Al-2.5Sn) having goodfracture toughness at room temperature and high temperature and goodheat-resistance and long-term working temperature of about 500° C. Inaddition, low-interstice Ti-5Al-2.5Sn is applicable to low-temperatureenvironment. Pure titanium and titanium alloy have nine properties ofhigh specific strength, excellent anticorrosion ability, low elasticmodulus, good heat-resistance, excellent low-temperature property, highbiological compatibility, low heat conductivity, colorful oxide film andnon-magnetic. Therefore, different types of commercial pure titanium ortitanium alloys or stainless steel are selectively used for differentsections of the loop heat pipe. According to the different features ofcommercial pure titanium and titanium alloys or stainless steel, theconventional copper or aluminum material can be replaced. This has theadvantages that the heat dissipation efficiency and structural strengthof the entire loop heat pipe are enhanced and the weight of the loopheat pipe is reduced.

Please refer to FIG. 3, which is a sectional assembled view of a secondembodiment of the loop heat structure of the present invention. Thesecond embodiment is partially identical to the first embodiment instructure and thus will not be redundantly described hereinafter. Thesecond embodiment is different from the first embodiment in that theoutlet 114 and the inlet 115 are disposed on different sides of theevaporation chamber body 11. The second end 122 of the tube body 12enters the closed chamber 113 from the inlet 115 of the evaporationchamber body 11 and extends to one side distal from the compensationchamber 117.

Please refer to FIG. 4, which is a sectional assembled view of a thirdembodiment of the loop heat structure of the present invention. Thethird embodiment is partially identical to the first embodiment instructure and thus will not be redundantly described hereinafter. Thethird embodiment is different from the first embodiment in that theevaporation chamber body 11 has a liquid passage 118. One end of theliquid passage 118 is connected with the inlet 115. The liquid passage118 is disposed on one side of the capillary structure 2. In addition,the liquid passage 118 and the vapor passage 116 are respectivelycorrespondingly disposed on upper and lower sides of the capillarystructure 2.

Please refer to FIG. 5, which is a sectional view showing the operationof the loop heat structure of the present invention. As shown in thedrawing, one side (heat contact face) of the evaporation chamber body 11of the loop heat pipe structure 1 of the present invention is in contactwith a heat source 5. The capillary structure 2 is correspondinglydisposed in a section of the evaporation chamber body 11 in contact withthe heat source 5. The capillary structure 2 contains the liquid-phaseworking fluid 32 therein. When the evaporation chamber body 11 contactsthe heat source 3 and absorbs the heat generated by the heat source 3,the internal capillary structure 2 is heated and the liquid-phaseworking fluid 32 contained in the capillary structure 2 is evaporated tospread from the vapor passage 116 and leave the capillary structure 2.One end of the vapor chamber 116 is directly connected with the outlet114 of the evaporation chamber body 11 so that the vapor-phase workingfluid 31 directly spreads from the outlet 114 to outer side of theevaporation chamber body 11. The first end 121 of the tube body 12 isconnected with the outlet 114 so that the vapor-phase working fluid 31enters the tube body 12. The vapor-phase working fluid 31 is cooled andcondensed in a position where the heat dissipation unit 4 is disposed on(stringed by) the tube body 12. The second end 122 of the tube body 12is connected with the inlet 115 of the evaporation chamber body 11 sothat the liquid-phase working fluid 32 is guided to flow back into theevaporation chamber body 11. When the liquid-phase working fluid 32 isevaporated, a pressure difference is created. By means of the pressuredifference and the capillary attraction, the liquid-phase working fluid32 can be guided to flow back into the capillary structure 2. Moreover,the inlet 115 is correspondingly disposed on upper side of the capillarystructure 2 so that due to gravity, the liquid-phase working fluid 32can further directly fall into the capillary structure 2 to continue thevapor-liquid circulation.

Alternatively, any other heat dissipation component (not shown) capableof enhancing condensation effect can be connected with or disposedaround the tube body 12 so as to enhance the condensation efficiency.

The other object of the present invention is to change the relativerelationship between the outlet 114 and the inlet 115 of the evaporationchamber body 11 and the capillary structure 2. When the liquid-phaseworking fluid 32 flows back into the evaporation chamber body 11, theliquid-phase working fluid 32 is first guided into the capillarystructure 2 serving as a vapor wick. That is, the capillary structure 2is directly disposed under the inlet 115 so that after the liquid-phaseworking fluid 32 flows back, the liquid-phase working fluid 32 firstenters the capillary structure 2 and is stored therein. After the watercontent of the capillary structure 2 is saturated, the excessiveliquid-phase working fluid 32 will enter the compensation chamber 117 tobe stored therein. This solves the problem of the conventionalflat-plate evaporator that the flat-plate evaporator is placedhorizontally so that the working fluid 2 of the compensation chamber isover-spaced from the evaporation face to cause dry burn.

The present invention mainly employs various materials in combinationwith each other as the materials of the respective sections of the loopheat pipe. Different materials are used with respect to differentsections so that not only the total weight is reduced, but also thestructural strength is increased. In addition, the present inventioneffectively provides heat conductivity or heat dissipation feature forthe heat absorption section or heat dissipation section. Moreover, bymeans of the arrangement of the internal capillary structure 2, thecompensation chamber 117 and the vapor passage 116, the shortcoming ofthe conventional loop heat pipe that the pressure impedance makes theliquid-phase working fluid 32 fail to flow back.

The present invention has been described with the above embodimentsthereof and it is understood that many changes and modifications in suchas the form or layout pattern or practicing step of the aboveembodiments can be carried out without departing from the scope and thespirit of the invention that is intended to be limited only by theappended claims.

What is claimed is:
 1. A loop heat pipe structure comprising: anevaporation chamber body having an upper case body and a lower boardbody, the upper case body and the lower board body together defining aclosed chamber in which a capillary structure is disposed, theevaporation chamber body having an outlet and an inlet in communicationwith the closed chamber, a working fluid being filled in the closedchamber; and a tube body having a first end, a second end and a middlesection, the first and second ends being respectively positioned at twoends of the middle section, the first and second ends being respectivelyconnected with the outlet and inlet of the evaporation chamber body, theupper case body, the lower board body and the tube body being made ofdifferent materials in combination with each other according torequirements, the materials being selected from a group consisting oftitanium, stainless steel, copper, ceramic, aluminum, iron and graphite.2. The loop heat pipe structure as claimed in claim 1, wherein a heatdissipation unit is disposed on outer side of the tube body, the heatdissipation unit being composed of multiple radiating fins or multiplecooling tube bodies.
 3. The loop heat pipe structure as claimed in claim1, wherein the closed chamber further has a compensation chamber and atleast one vapor passage, one end of the vapor passage being incommunication with the outlet.
 4. The loop heat pipe structure asclaimed in claim 3, wherein the vapor passage is selectively disposed ona wall face of the evaporation chamber body, which faces the capillarystructure or disposed on one side of the capillary structure, whichfaces the evaporation chamber body, one end of the vapor passage beingcorrespondingly connected with the outlet, the working fluid beingconverted between vapor phase and liquid phase, the vapor-phase workingfluid and the liquid-phase working fluid being circulated within theentire interior of the loop heat pipe structure.
 5. The loop heat pipestructure as claimed in claim 3, wherein the vapor passage isselectively disposed on a wall face of the evaporation chamber body,which faces the capillary structure or disposed on one side of thecapillary structure, which faces the evaporation chamber body, one endof the vapor passage being correspondingly connected with the outlet,the working fluid being converted between vapor phase and liquid phase,the vapor-phase working fluid and the liquid-phase working fluid beingcirculated within the entire interior of the loop heat pipe structure.6. The loop heat pipe structure as claimed in claim 3, wherein theoutlet and the inlet are disposed on different sides of the evaporationchamber body, the second end of the tube body entering the closedchamber from the inlet of the evaporation chamber body and extending toone side distal from the compensation chamber.
 7. The loop heat pipestructure as claimed in claim 3, wherein the evaporation chamber body isa flat-plate evaporation chamber body, the compensation chamber beingcorrespondingly disposed in parallel to the capillary structure.
 8. Theloop heat pipe structure as claimed in claim 1, wherein the evaporationchamber body has a liquid passage, one end of the liquid passage beingconnected with the inlet, the liquid passage being disposed on one sideof the capillary structure, the liquid passage and the vapor passagebeing respectively correspondingly disposed on upper and lower sides ofthe capillary structure.
 9. The loop heat pipe structure as claimed inclaim 1, wherein the capillary structure has multiple channels inadjacency to the lower board body, each channel having an open side anda closed side, the open side being attached to the lower board body, theopen side having a width smaller than that of the closed side.
 10. Theloop heat pipe structure as claimed in claim 1, wherein the capillarystructure is formed of sintered powder, the powder being selected from agroup consisting of copper, aluminum, titanium and plastic fiber.